In the following video from SciShow you can hear from Victoria Orphan, a MacArthur Fellow. She is a geobiologist who studies the interrelationship of organisms and their environment. One area she is especially interested in the influence of microbes on the chemistry of environments, and looks into the past for clues by way of signatures that ancient events have left behind.
One topic they discuss is methane in the deep sea; while they are not well-understood, geobiologists are looking at layers of ice in the deep sea that contain methane - methane hydrates - and how they interplay with microbes in the deep ocean. Some microbes can consume methane, and some can use oxygen to help them obtain energy from that methane, others can even use salt instead as a conduit for harvesting energy from the methane. Researchers also look into the byproducts of such reactions, and how those might impact the environment.
This type of work could be critical in the future as people deal with the consequences of climate change; methane could play a major role in the process, and understanding its role is important for us and the planet.